TY - JOUR
T1 - Investigation of a magnetic tunnel junction based sensor for the detection of defects in reinforced concrete at high lift-off
AU - Sam, Muhamad Arif Ihsan Mohd Noor
AU - Jin, Zhenhu
AU - Oogane, Mikihiko
AU - Ando, Yasuo
N1 - Funding Information:
Acknowledgments: This work was supported by SCOPE project, Center for Science and Innovation in Spintronics, and Center for Spintronics Research Network, Tohoku University. The authors would like to extend their gratitude to Tohoku University’s Spin Sensing Factory (SSF) and Kosuke Fujiwara for supplying the MTJ sensors used in this research. Special thanks to Japan Railway (JR) West for providing the reinforced concrete sample. The authors would also like to thank Hiroshi Wagatsuma for his help in the design and construction of the circuit.
Funding Information:
This work was supported by SCOPE project, Center for Science and Innovation in Spintronics, and Center for Spintronics Research Network, Tohoku University. The authors would like to extend their gratitude to Tohoku University?s Spin Sensing Factory (SSF) and Kosuke Fujiwara for supplying the MTJ sensors used in this research. Special thanks to Japan Railway (JR)West for providing the reinforced concrete sample. The authors would also like to thank Hiroshi Wagatsuma for his help in the design and construction of the circuit.
Publisher Copyright:
© 2019 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2019/11/1
Y1 - 2019/11/1
N2 - Magnetic flux leakage (MFL) testing is a method of non-destructive testing (NDT), whereby the material is magnetized, and when a defect is present, the magnetic flux lines break out of the material. The magnitude of the leaked magnetic flux decreases as the lift-off (distance from the material) increases. Therefore, for detection at high lift-off, a sensitive magnetic sensor is required. To increase the output sensitivity, this paper proposes the application of magnetic tunnel junction (MTJ) sensors in a bridge circuit for the NDT of reinforced concrete at high lift-off. MTJ sensors were connected to a full-bridge circuit, where one side of the arm has two MTJ sensors connected in series, and the other contains a resistor and a variable resistor. Their responses towards a bias magnetic field were measured, and, based on the results, the sensor circuit sensitivity was 0.135 mV/mT. Finally, a reinforced concrete specimen with a 1 cm gap in the center was detected. The sensor module (with an amplifier and low pass filter circuits) could determine the gap even at 50 cm, suggesting that MTJ sensors have the potential to detect defects at high lift-off values and have a promising future in the field of NDT.
AB - Magnetic flux leakage (MFL) testing is a method of non-destructive testing (NDT), whereby the material is magnetized, and when a defect is present, the magnetic flux lines break out of the material. The magnitude of the leaked magnetic flux decreases as the lift-off (distance from the material) increases. Therefore, for detection at high lift-off, a sensitive magnetic sensor is required. To increase the output sensitivity, this paper proposes the application of magnetic tunnel junction (MTJ) sensors in a bridge circuit for the NDT of reinforced concrete at high lift-off. MTJ sensors were connected to a full-bridge circuit, where one side of the arm has two MTJ sensors connected in series, and the other contains a resistor and a variable resistor. Their responses towards a bias magnetic field were measured, and, based on the results, the sensor circuit sensitivity was 0.135 mV/mT. Finally, a reinforced concrete specimen with a 1 cm gap in the center was detected. The sensor module (with an amplifier and low pass filter circuits) could determine the gap even at 50 cm, suggesting that MTJ sensors have the potential to detect defects at high lift-off values and have a promising future in the field of NDT.
KW - Lift-off
KW - Magnetic tunnel junction sensors
KW - Non-destructive testing
KW - Reinforced concrete
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U2 - 10.3390/s19214718
DO - 10.3390/s19214718
M3 - Article
C2 - 31671677
AN - SCOPUS:85074345398
SN - 1424-8220
VL - 19
JO - Sensors (Switzerland)
JF - Sensors (Switzerland)
IS - 21
M1 - 4718
ER -